I think only few ICOs pay their signature bounty in altcoins or their native currencies. In most cases, a lot of signature campaigns pay in bitcoin, which in my opinion is not a bad idea.

Mostly, social media and translation bounties are the ones which offers altcoin payouts, either in their native currency or most popular cryptocurrencies. If you are willing to participate in one, I would recommend that you go through subforum altcoins' marketplace. Good luck.